Helical activator for electrodeposition

ABSTRACT

An activator device for use in a process wherein mechanical activation of the electrodeposit is carried out during the electrodepostion reaction, such activator device being formed in the configuration of a helix having as the outer portion thereof a firm backing capable of deformation into and retention of a desired shape and a coextending inner laminate of porous, compressible, resilient, hard particle- carrying material.

HELICAL ACTIVATOR FOR ELECTRODEPOSITION Filed Sept. 11, 1972 United States Patent 3,795,602 HELICAL ACTIVATOR FOR ELECTRODEPOSITION Carl H. Rowe, Scotia, N.Y., assignor to Norton Company, Troy, N.Y.

Filed Sept. 11, 1972, Ser. No. 288,047 Int. Cl. C23b /68 US. Cl. 204-209 6 Claims ABSTRACT OF THE DISCLOSURE An activator device for use in a process wherein mechanical activation of the electrodeposit is carried out during the electrodeposition reaction, -such activator device being formed in the configuration of a helix having as the outer portion thereof a firm backing capable of deformation into and retention of a desired shape and a coextending inner laminate of porous, compressible, resilient, hard particle-carrying material. l

FIELD OF THE INVENTION The present invention relates generally to electrodeposition and more specifically to electrodeposition on elongate, small cross-section substrates generally continuous or at least very long in relation to their diameters, e.g. wire, tubing, narrow fiat strip, etc. Also, the present invention specifically relates to a particular type of electrodeposition wherein a plurality of small hard particles are utilized to mechanically activate the surface of the electrodeposit throughout its formation. Such a process, hereinafter referred to as the N-E-T Process for convenience, is illustrated and claimed in US. Letters Pat. No. 3,619,384, entitled, Electrodeposition, and issued to Steve Eisner on Nov. 9, 1971.

RELATED ART Wire, tube and similar continuous small cross-section materials have conventionally been electroplated at higher speeds than most other items. By moving the small diameter wire, tube or narrow strip through plating baths at high linear rates, the agitation of the electrolyte due to such passage has apparently produced a thinning of the diffusion or polarization layer at the surface of the wire or the like, permitting the use of higher current densities than could be achieved in the absence of such movement.

The aforementioned N-E-T Process has provided a still further speed increase by introducing small hard particles into contact with the electrodeposit as it forms and mechanically activating the surface of such electrodeposit throughout its formation. US. 3,619,401 and the copending applications, Ser. Nos. 256,884 and 280,569, referred to above, each disclose and claim apparatus for utilization of such N-E-T Process.

SUMMARY OF THE INVENTION By shaping a hard particle-carrying activator in the general form of a helix as is described below, it can be utilized either as a stationary activator through which a continuous workpiece is pulled at relatively high speed or it can be 3,795,602 Patented Mar. 5, 1974 utilized as a driven activator working on a substrate which may be static or which may be moving laterally through the activator as the activator rotates. One modification illustrated herein cannot be driven but must be used as a static activatori.e. where the cross section of the helix 1s non-circular, it must be used as a static unit.

The helical structure permits electrolyte flow into the plating zone, interior of the activator, by providing narrow openings between adjacent turns of the helix. It also uniformly wraps the elongate workpiece with an almost continuous activator surface so it will produce uniform activation and hence plating. Further, it permits easy changing of the activator by merely wrapping or unwrapping the helix from around the elongate workpiece, thereby permitting changing of the activator without interfering with the passage of the workpiece through the plating area. Finally, by twisting the helix ends in opposite directions, the compressive force exerted by the material of the helix against the workpiece can be adjusted and controlled. Means can readily be provided on the outer surface of the helix to engage rotatably-driven means so as to cause the activator to rotate about the workpiece (Where the cross section of the workpiece is circular).

DRAWINGS FIG. 1 is a schematic view illustrating an activator device of the present invention partially opened up in order to exhibit its structure.

FIG. 2 illustrates a modified device adapted for use with a rectangular cross-section workpiece.

FIG. 3 schematically illustrates in cross section an activator device of the present invention used as static activator with a moving substrate.

FIG. 4 schematically illustrates an activator device of the present invention used as a driven activator with a static substrate.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to the drawings, FIG. 1 shows a partially-formed activator device 10 made up of an inert anode strip 11 with a coextensive, adhered inner liner of porous, fibrous material 12 having a plurality of small, hard activating particles 13 adhered in spaced relationship to at least the exposed inner surface of such liner material 12. In accordance with the present invention, the inert anode strip 11 and its associated inner liner 12 is formed into a helix as at 14 with the inner diameter of such helix being just slightly less than the diameter of the workpiece to be inserted therein so that when in place the inner liner material 12 will be at least slightly compressed. As illustrated here, the device 10 is intended for operation on a workpiece of circular diameter, e.g. a tube, wire, etc. The gaps 15 between the helix windings 14 provide entry for electrolyte when the device 10 is used in a plating process.

A similar device 20, intended for use with a rectangular cross-section workpiece, is shown in FIG. 2. Here, since with a rectangular configuration the activator device 20 must be used as a static member with the activation provided by the motion of the workpiece, the rectangular workpiece 21 is shown and is indicated as moving by the arrow. Surrounding and in close engagement with the surfaces of the workpiece 21 is the particle-carrying, porous compressible inner liner 23. The outer, inert anode 22 has a corresponding rectangular cross section while forming the spaced helix sections 24. Again, the spaces 25 between the helix windings 24 provide openings for electrolyte flow 1n use.

FIG. 3 illustrates the manner in which an activator device of the present invention is utilized as a static member through which an elongate substrate to be plated is moved at relatively high speed. The device 30 is shown in cross 3 section imposition on -an..elongate workpiece 3l= moving under the surface of the electrolyte 36 in the direction of the arrow. The helical activator has an outer inert anode shell. 32 and an inner liner of hard-particle-carrying, prous, compressible activator material 33 pressed by the configuration of the anode shell 32 into intimate contact witth the surfaces of the moving workpiece (cathodic) 31. The plurality of openings 34 between the windings of the helix device allow for flow of electrolyte 36 into the plating zone interior of such helix. With a stationary or static unit such as illustrated here, auxiliary pumping is usually necessary. Here a distributor 37 is shown with an opening 38 through whichelectrolyte 36 is pumped (by any suitable conventional pumping means not shown) into a collecting chamber 39 from whence it is fed via tubes 40 into-the slots or openings 34 in helix device 30. Spent electrolyte 36 exits through the bottom openings 34 as indicated by the arrows.

FIG. 4 illustrates a system wherein an activator device according to the present invention is not static but is itself driven rotatably about a workpiece extending therethrough. Here, the workpiece 51 is shown'as static, but obviously it can be moved laterally in conjunction-with the rotation of the activator device 50 if desired. The unit 50 and workpiece 51 are shown completely immersed below the surface of electrolyte 52. As indicated, the helical unit 50 has its outer shell anodic while the workpiece 51 is cathodic. The two outer or end helical wraps 50a and 50b are here shown as being provided with a knurled or non-slip surface so that when they are contacted by drive wheels 53, good frictional contact will result and the device 50 will be rotated about workpiece 51. Drive Wheels 53 are rotatably driven by belt 56 engaging with the central drive pulley 54 which in turn is connected to drive wheels 53 through shafts 55. Belt 56 is driven by drive pulley 57, external of electrolyte 52, which in turn is connected to a suitable motive-force providing unit such as motor 58.

In all of these systems, means must be provided to keep the helix unit in closed position about the workpiece. Usually, this is accomplished by the nature of the anode --strip used to form the helix. Where lead or similar inert metal is used, once the helix is formed by bending the anode material, it will retain its shape without the use of .supplemental fastening means. Should this not be the case, thenv a plastic clip around each end wrap of the helix beneath it builds up. With a moving workpiece," the only adjustment usually required is to tighten the helix as the .activator material on its interior is worn down by passage of the workpiece. Where the helix is rotated as illuss saeoz 7 I -=-t-ratedinFIG. 4, the angle of-the-slots or openings'between the helical windings will tend to act like pump vanes pulling electrolyte into one side of the slot and expelling it from the other. However, in all instances, auxiliary electrolyte pumping may be employed if desired or necessary.

Iclaim: I H

1. Apparatusrfor electroplating elongate cathodic members having substantially-uniform cross-sectional areas throughout their length which comprisesn (a) a helical-wound activator adapted'to closely surround and engage the surfaces of such an elongate member below the surfiicldf an electrolyte bath;

(b) means to provide relative. motion bet-ween the surfaces of such elongate. member and said activator;

(c) means to providean imposed electrodeposition current flow;,and

(d) means to supply electrolyte flow to the interior of said activator adjacent said surfaces of said elongate member.

2. Apparatus as in claim 1 wherein said means to provide relative motion between the surfaces of the elongate member and the activator'includes means to hold the helical-Wound activator stationary as the elongate workpiece is moved laterally therethrough. v.

3. Apparatus as in claim 1 wherein said means to provide relative motion between the surfaces of the elongate member and the activator includes means to rotatably drive the helical-wound activator about the circumference of said elongate workpiece. 1 1

4. Apparatus as in claim 1 including means to apply a twisting force to the ends, of said helical-wound 'a ctivator to adjust the engagement of such activator with the surfaces of said elongate member.

5. Apparatus as in claim 1 wherein saidh'elicabwound activator is made up of an outer narrow strip of material capable of deformation into and retention of a 'desire'd shape and an inner strip coextensive with and afiixed to said outer strip, said inner strip being a porous, compressible, resilient, hard particle-carrying material;

6. Apparatus as in claim 5 wherein said outer narrow strip is'made up of an inert metal.

References Cited w I I IITED STATES' 3,022,232] 2/1962 Baileyfet 1:- 2Q DIG. 10 3,619,383 11/1971 Eisner, 2044310, 10

FOREIGN 'PATENIS 18,643 8/1900 Great Britain 204TDIG.l0 JOHN H. MACK, Primary Examiner W..I. SOLOMGN, Assistant Examiner US. Cl. X.R. 2O4- 2 7, 28, 35 R, 217, Dig. 10 

